Cam actuated steering by driving



May 4, 1954 J. A. RONNING 2,677,432

CAM ACTUATED STEERING BY DRIVING Filed Sept. 26, 1949 6 Sheets-Sheei'l lMay 4, 1954 J. A. RONNING 2,677,432

CAM ACTUATED STEERING BY DRIVING Filed Sept. 26, 1949 6 Sheets-511661l 2May 4, 1954 J. A. RoNNlNG 2,677,432 CAM AC'IUATIID STEERING BY DRIVINGFiled Sept. 26, 1949 6 Sheets-Sheet 5 J. A. RONNING 2,677,432P` CAMACTUATED STEERING BY DRIVING 6 Sheets-Sheet 4 May 4, 1954 Filed Sept.26, 1949 May 4, 1954 J. A. RoNNlNG 2,677,432

CAM ACTUATED STEERING BY DRIVING Filed sept. 2e. 1949 s sheets-sheet 5May 4, 1954 J. A. RONNING 2,677,432

CAM ACTUATED STEERING BY DRIVING Filed Sept. 26, 1949 6 Sheets-Sheet 6 lmln p 30 /201 73] Patented May 4, 1 954 UNITED STATES 7 Claims.

My present invention relates to self-powered vehicles, and moreparticularly to relatively lowspeed vehicles oi the kind commonlyreferred to tractors, and which are generally employed for performingvarious work functions, such as pulling or pushing loads or carryingdifferent kinds or types of implements or devices.

@ne important object of the present invention is the provision of anextremely simple lowcost power-transmission mechanism foil Selfpoweredvehicles.

Another important object of the invention is the provision of aself-powered vehicle having great maneuverability, making it possible towork in unusually close quarters and among obstructions which wouldseriously hamper conventional vehi les.

mother important object of the invention is the provision of an improvedpower transmission mechanism interposed between the prime mover orengine of a vehicle and the laterallyspaced drive wheel thereof, havinginherent characteristics allowing a diierence in speed between the drivewheels to facilitate turning of the vehicle without the use ofexpensive, complicated differential mechanisms or other auxiliarydevices or apparatus.

Another important objective of the invention is the provision of animproved friction-type power transmission mechanism for vehicles of theclass described.

The above and. other highly important objects of the invention will bemade apparent from the following specification, claims, and appendeddrawings.

ln the accompanying drawings, like characters indicate like partsthroughout the several views.

Referring to the drawings:

Fig. l is a view in elevation, with some parts broken away and someparts shown in section, oi a vehicle, in the nature of a tractor,incorporating a preferred embodiment of the invention;

Fig. 2 is an enlarged fragmentary view of the machine shown in Fig. l,showing some parts in top plan and some parts sectioned on the line l--ici Fig. l'

ll- A.,

fig. 3, Ll and 5 are enlarged fragmentary secviews, taken on the line3-3 of Fig, 2, and showing dinerent positions of the parts;

Fig. 6 is an enlarged sectional detail view, with parte broken away,taken on the line 6-5 of Fig. 2;

Fig. is a detail sectional View, taken on the line l-l of Fig. 3;

Fig. 8 is a detail sectional line t-B of Fig. '7;

View, taken on the Fig. 9 is an enlarged detail sectional view, taken onthe line 9-9 of Fig. 1;

Fig. l0 is a fragmentary view corresponding to Fig. 3, out showing asomewhat modified form of the invention; and

Fig. ll is a fragmentary plan view of that portion of the machine shownin Fig. l0.

First to be described will be Figs. 1 to 9, inclusive, and the preferredembodiment of the invention disclosed therein. Referring to thesefigures, the vehicle disclosed in these figures comprises a generallyhorizontal frame structure l, laterally-spaced ground-engaging drivewheels 2, and a steerable ground wheel rlhe drive wheels 2 areindependently journalled on a common stationary axle A, which latter ismounted on the frame l through the medium of brackets 5. The steerablewheel, which in this instance is at the rear of the machine, isjournalled at t in the lower end portion of a steering fork l, whichlatter is vertically journalled for steering movements at 8 in a crossmember 9 of frame i. The vehicle shown is provided with an operatorsseat IS, mounted on the rearwardly-projected end portion of a rearwardlyextending auxiliary frame structure l E, that is pivoted to theintermediate portion of frame l at i2, the seat l and underlying portionof frame ll being resiliently supported from the frame structure ithrough the medium of a coil compression spring or springs For impartingsteering movements to the sterable wheel 3, there is provided a steeringgear comprising a journalled steering post lli and a steering wheel i5.The steering post Hl is journalled adjacent its lower end to the framestructure I through the medium of a suitable bearing sleeve it andframe-supported bearing brackets il and it. The steering post irl isoperatively coupled to the fork l of the steerable wheel t by linkagecomprising a beveled gear it fast on the steering post lil, cooperatinggear segment 2t fast on a frame journalled sleeve t', a shaft 2l mountedfor rotary and axial sliding movements in sleeve 2G (see Fig. 6), achain sprocket 22 also fast on sleeve 2t', and a link chain 23 runningover sprocket 22, and a sprocket fl fast on the journalled portion li offork l'.

The vehicles prime mover is indicated as an entirety by 25, which, asshown, is in the nature of a conventional internal combustion gas enginesupplied with liquid fuel from a suitable tank 26 and provided with anexhaust muffler 2l.

interposed between the engine 2li and drive wheels 2 are two likespeed-reducing direction reversing power transmission mechanisms, eachindicated as an entirety by 28 and each driving a diierent drive wheel2. Preferably, and as illustrated, each of these transmission mechanisms28 is of the friction type comprising a pair of engine-driven rollerelements 29 and 30, and a roller-driven wheel driving drum element 3l.The engine-driven roller elements 29 of opposite transmission mechanisms28 are mounted fast on opposite ends of a shaft 32, and the rollerelements 35 of opposite transmission mechanisms 28 are mounted fast onopposite ends of a shaft 33 (see particularly Fig. 7). The shafts 32 and33 are journalled in opposite sides of a transmission gear case 34mounted fast on the frame structure l and located between thefriction-type transmission mechanisms The roller elements 29 and Se ofthe transmission mechanisms 23 are, preferabh and as shown, constantlydriven in opposite directions from the engine through drivingconnections comprising intermeshing spur gears 35 and 35 fast on shafts33 and 32, respectively, a direction reversing gear 57 intermeshing withgear t and mounted fast on a shaft 3l", a gear S8 fast on a shaft SS, abelt pulley 3Q fast on the outer end of shaft and an engine-driven 'neitd5, the latter being sumed to be driven from the engine through themedium of an engine shaft mounted pulley, not shown. The shaft 38 isjournalled in suitable bearings in opposite sides of the gear case 35s.

The roller-driven drum elements 3l of the opposite transmissionmechanisms are each coupled to an opposite drive wheel 2 by drivingconnections comprising a drum-driven shaft 4i es:- tending axiallyoutwardly from and mounted fast in its respective drum Si, a chainsprocket d2 fast on the outer end of each shaft lil, a chain sprocket e3fast on each drive wheel 2, and link drive chains dil running overcooperating chain sprockets l2 and t3.

The rims of the drums 3i are internally provided with friction facingsfor friction engagement with their respective cooperating rollers 29 and3G. Each transmission mechanism 23 provides neutral, forward and reversedrive for its respective wheel 2. The rollers 25 and 3! are preferablyof steel throughout and are both spaced from their respectivecooperating drum Si when their respective transmission mechanisms are inneutral, as shown, for example, in Fig. 3. In the arrangementillustrated, the drums 3i revolve in the same direction as do the Wheels2, the rollers 2S being engine-driven in a direction to produce forwarddrive rotation of drums 3l, and the roller elements 5t beingenginedriven in a direction to produce rearward drive of theirrespective drums. Shifting of the transmission mechanisms is achieved byrelative shifting of the rollers with respect to the drums. In` thearrangement illustrated, shifting of the transmission mechanisms 28 fromneutral position, shown in Fig. 3, to forward drive position, shown inFig. 5, or reverse drive position, as shown in Fig. 4, is accomplishedby shifting the drums 3l from neutral position of Fig. 3 to forwarddrive position of Fig. 5 or reverse drive position of Fig. 4. For this,purpose, the drums 3i are mounted from the frame structure l forshifting movements with respect to said frame through a mechanism asfollows: The shaft 4l of each drum 3| is journalled in a long bearingsleeve 46, mounted fast on the rearwardly-extended end of an oppositeone of a pair of oscillatory arms 4l; the oscillatory drum-mounting armsdi being pivoted at their front end portions to the frame structure I atA8. It will now be obvious that shifting of either of the drums 3l onits mounting axis i8 in a counterclockwise direction wtih respect toFig. 3 through Fig. 5, will shift that transmission mechanism fromneutral drive to forward drive, and that shifting of the drum 3| ofeither transmission mechanism on its axis 48 in a clockwise directionwith respect to Fig. 3 through Fig. 5 will produce forward drive of thattransmission.

The bearing sleeve of each transmission mechanism 28 is equipped with arigidly-anchored rearwardly-projecting shifter arm 4t, which, in thepreferred embodiment of the invention illustrated, is provided at itsfree rear end portion with a bifurcated fork-like shifter head 50,providing outwardly-diverging cam surfaces 5I and 52. For the purpose ofselectively but simultaneously shifting the drums 3l of transmissions 28from neutral to forward or reverse drive, I provide shifting mechanismcomprising a manually-operated shifting lever 53 fast on a rock shaft54, a pair of r ck arms E, a pair of rigid links or rods 56, and opposedresilient links in the form of compression springs 5'! and 58. The rocksha t 54 is journalled in suitable bearings carried by the framestructure l, and the rock arms 55 are fast on rock shaft 54. Each rockarm 55 is pivoted to the lower end of a different one of said links 56,and each thereof work slidably through a ange 5S of a dilferent one ofsaid shifter arms 49. The springs 5l and 53 of each rigid link 56 aretelescopically applied thereon and engage opposite sides of a shifterarm flange 59. The springs 5l and 58 are maintained under compressionagainst opposite sides of the shifter arm flanges 59 by means ofcompression adjusting nuts 60 screw-threaded on the rigid links or rods56.

The shifting lever 53, as shown, is a composite structure comprising themain shank or stem thereof, a rigid head 6i and a yoke t2; the head Gibeing pivoted in the yoke 62 for lateral swinging movements, and theyoke 62 being fast on rock shaft 54. For the purpose of maintaining theshifter lever 53 in selectively adjusted positions, there is provided atoothed segment 53 mounted fast on the frame structure l (seeparticularly Fig. 9), and a cooperating dog or detent Eid fast on lever53, and which is moved into and out of intermeshing engagement with theteeth of segment 52 by lateral movements of shifter lever or arm 53 on(seo Figs. l and 9) The shifting lever 3 is maintained under yieldingpressure to move its detent fi into intermeshing engagement with theteeth of seg'- ment @3 by means of a coil compression spring 56, Fromthe above, the following should oe apparent, to wit:

(A) When the shifting lever is in its intermediate position, as shown inFig. l, the drum elements 3| of both transmission mechanisms 23 will beout of frictional engagement with their cooperating roller elements and3S, as sl'aov/n best in Fig. 3; both transmission mechanisms being thenin neutral drive;

(B) When the shifting lever is moved forwardly from its intermediateposition of Fig. the drums 3l of both transmission mechanisms 28 will beshifted toward and into engagement with their respective cooperatingforward drive roller elements 29 to produce forward drive of the wheels2;

(C) When the shifting lever 53 is moved rearwardly from its intermediateposition of Fig. 1, the

drum elements 3| of both transmission mechanisms 2d will be shifted intoengagement with their respective cooperating friction drive rollerelements 3|! to produce rearward drive to the wheels 2; and

(D) Speed or ratio of drive between the engine 25 and wheels 2 beingvariable in either forward drive or reverse drive depending upon theamount of slippage allowed between the drum elements 3| and theirrespective cooperating roller elements 29 or ist; this factor beingdetermined by the amount of pressure applied between the drum elements3| and cooperating roller elements 29 or 59, which is, in turn,controlled by the amount of compression of springs l or 58 afterengagement of drum elements 3| with their cooperating roller elements 29or 39 through the medium of shifting lever 53, rock shaft 54, rock arm55 and rod or link 5t.

In carrying out the invention, the dir-ection or angle of approachbetween the drum elements 3l and the roller elements 29 and 39,respectively, is very important. In this connection it will beunderstood that if the angle of approach between the drum elements 3|and roller elements 29 and 3d be in, or substantially in, a plane radialto the axis of the drum elements 3| and the axes of engaged rollerelements 29 and 30, the frictional driving force or pressure exertedbetween the drum elements 3| and engaged roller elements 29 or 39 willbe neither increased or decreased as a result of frictional drivingforce -exerted by engaged roller elements 29 or 30 with their respectivecooperating drum elements 3i; the pressure of force between the engagedroller elements 29 or 3S with their drum elements 3| being then, infact, the same regardless of whether the driving energy is applied bythe rollers to the drum elements or by the drums to the roller elements.

As an important feature of the present invention, the angle or directionof approach of the drum elements 3| of the transmission mechanisms 28 totheir respective cooperating roller elements 29 and 3U is such that thedriving energy frictionally transmitted from the roller elements 29 and3Q to the drum elements 9| will tend to draw the engaged drum and rollerelements into tighter and tighter frictional engagement under increasesin driving torque transmitted from the roller elements to the drumelements; the resultant increase in frictional pressure between thedrums and rollers being additive to that being at the time exerted bythe drum elements 3| on their respective engaged roller elements 29 or39 by compression springs 51 or 58. By particular reference to Fig. 3,it will be seen that this action is achieved, in the present instance,by mounting the drums for shifting movements on shifting axes 48, whichare radially outwardly of the drums in one direction, and by spacing therollers 2s and 3e of each mechanism apart less than 186 with relation tothe drum rotation axis and radially outwardly of the drum rotation axisin a direction opposite the shifting axis 43 of the drum; the center ofa triangle drawn between the drum shifting axis d8 and the axes ofrollers 23 and 39 being in a plane through axis 48 and the axis ofrotation of the drum 3| when said drum is in its centered neutralposition of Fig. 3. In the particular example given, the rollers 29 and35 are spaced apart approximately 134, as measured on an arc concentricwith the axis of a neutrally positioned drum 3| and located on the sideof the drum rotation axis opposite the drum shifting axis 48. In otherwords, in the present example, the rollers 29 and 39 arecircumferentially spaced approximately 67 in opposite directions from aplane extending through the axes 428 and 4i when the drum is in itscentered neutral position of Fig. 3 when measured on an arc spaced fromthe axis il in a direction opposite the shifting axis 138'.

Although the drums are actually shifted in an arcuate path, the extentof movement of the drums after an initial engagement with rollers 29 or39 is so small that the result is substantially identical to that whichwill be achieved by straight-line shifting movements of the drum. Hence,in accordance with the present example, it may be said that the angle ofapproach of each drum 3| to its rollers 29 and 3D, respectively, is thearcuate or angular distance between one plane that is tangent to an archaving its axis at the drum shifting axis 48 and intersecting the pointof contact between the engaged roller 29 or 39 and drum and anotherplane tangential to the engaged surfaces of drum and roller 2t or 39 atthe point of contact therebetween and which, in the present instance, isapproximately 42. In the present instance, the last-mentioned planes arespaced from the rst-mentioned planes in the direction of rotation of thedrum under the iniluence of its engaged roller element 29 or t9.However, if the structure were such that the roller elements 22 and 30were shifted and drums were stationary, then the condition last-aboveexpressed would be just reversed. It should be understood that theextent of increased pressure between engaged rollers and drums as aresult of driving torque or force applied to the drums through therollers may be increased by decreasing the so-called angles of approachof the drum to the rollers 29 and 30 and may be decreased by increasingthe angles of approach of the drums to the rollers 29 and 39, up to amaximum of when said angles of approach are arrived at on the basisabove given.

With the angle and direction of approach of the drums 3| to the rollers29 and 39, as herein illustrated and described, for example, thepressure between the drums and engaged rollers is not only increased asa result of the transfer of driving energy from the rollers to thedrums, but is similarly decreased as a result of driving energy beingtransmitted from the drums to the rollers. This dual function is highlyimportant for the following reasons, to wit:

(A) When the drums are being driven from the engine-driven rollers,increased torque on the rollers automatically increases the friction andtorque-transferring ability between the engine-driven rollers androller-driven drums, which automatically maintains a comparativelyuniform slippage factor under quite wide variations in torque transferbetween rollers and drums; and

(B) When the drums apply driving force to the rollers, as do the outsidewheels 2 when making a turn, the drums tend to move away from theirengaged roller elements 29 or 30 against the action of the springs 51 or'58 to automatically decrease the frictional driving resistance betweenthe drums and rollers, thereby greatly facilitating steering of thevehicle by means of the steerable wheel 3, by allowing the drums to slipwith their respective cooperating engaged rollers 29 and 3i) and runahead thereof when torque transfer is from drums to rollers. By thisaction, a differential eifect is automatically obtained allowing thedrive Wheels 2 to run one ahead of the other when the vehicle is turnedresponsive to turning action of the steerable wheel 3.

To further increase the maneuverability of the vehicle described, Ipreferably provide steering gear-controlled transmission shiftingmechanism, presently to be described, and which, in the preferredembodiment of the invention under consideration, is ineffective underintermediate steering movements of the steering gear and steerable wheel3 to either side of a normal straight-ahead condition of the steeringgear and steerable wheel. This steering gear-controlled transmissionshifting mechanism, as illustrated in Figs. l, 3, 4, and 6, comprisesthe forked head of the shifting arm 4S of each transmission mechanism28, an oscillatory arm 61 mounted fast on the upper end of steering gearshaft 2l, a short rock arm 6s having one end mounted fast on rock shaft54, said rock shaft Eli, the rock arms 55, the rigid links or rods 55,the compression springs 5i and 53, and the shifter arms 48 of thetransmission mechanisms 2E. The short rock arm @3 is forked orbifurcated at its outer end to receive the lower end of shaft 2 l towhich it is coupled for sliding movements only with the shaft 2l, bymea-ns of opposed pins 5S working in an annular channel in in shaft 2 l.With this arrangement, vertical reciprocating movements of the shaft 2iare transferred to the rock arm SB and parts rigid therewith, but theshaft 2i is free to rotate on its axis independently of the rock arm 68.By particular reference to 6, it will be seen that the shaft 2i iscoupled to the sleeve 26 for rotary movements therewith by means of aset screw l i having a reduced diameter head which works in a key-waylike slot 'l2 of shaft 2i, which latter' allows the shaft 2l to workaxially within the sleeve 29'.

By reference now particularly to Fig. 2, it will be seen that thesteering gear-operated oscillatory arm Si faces rearwardly of themachine and is positioned in circumferentially-spaced relation inopposite directions to the forked heads El) of shifter arms i9 ofopposite transmission mechanisms 28 when the steerable wheel t is in aposition to produce straight-line movement of the vehicle. By referenceto this Fig. 2, it will also be seen that this oscillatory arm 6l isgenerally rectangular in cross-section providing two pairs of camsurfaces and that considerable turning movements of the vehicle guidingmeans comprising the steerable wheel and steering gear, to either sideof the straight-line of position shown in Fig. 2, will be required tobring a cam surface of the oscillatory arm 61 into engagement witheither of the shifter arm heads Hence, throughout the intermediateoperating range of the steering gear and steerable wheel, thesteering-gear operated transmission shifting mechanism will beinoperative. l-lowever, by reference to Fig. 2, it will be equally clearthat steering movements of the steering gear and steerable wheel 3 ineither direction from the normal straight-line position of Fig. 2 beyondthe intermediate range of the steering gear, will bring the oscillatoryarm 6i into one or the other of the bifurcated or forked shifter armheads With the arrangement illus.- trated, relatively sharp right-handturning movements of the steering gear and steerable wheel i will bringthe oscillatory arm 6l into engagement with the head '5t of thetransmission mechanism 28 driving the right-hand drive wheel 2, andrelatively sharp left-hand movements of the steering gear and steerablewheel 3 will bring the oscillatory arm 61 into engagement with the head5l! of the transmission mechanism 28 driving the left-hand drive Wheel2. Before going further, it is desired to call attention to the factthat the gear segment 20, as shown, is in the nature of a segmentalplate 13 having a section of link roller chain 'I4 applied around itssegmental surface and anchored thereto to provide roller teeth forintermeshing engagement with the teeth of beveled gear I9.

When the transmission shifting lever 53 is in its neutral position ofFig. l, the vertical centers of the bifurcated shifter heads 5l) ofopposite transmission mechanisms 28 will lie in a common horizontalplane, which will also be common to the vertical center of theoscillatory arm 61, all as shown in Figs. l and 3. However, when theshifting lever i3 is moved forwardly to its forward drive position, thebifurcated shifter heads 59 of both transmission mechanisms 28 will bedropped to the position shown in Fig. 5, wherein it will be noted thatthe oscillatory arm 61 is now aligned with the upper cam surfaces 5| ofeach of the bifureated shifter heads 50, and when the shifter lever S3is moved rearwardly to its reverse drive position, the bifurcatedshifter heads of opposite transmission mechanisms 28 will be raised tothe position shown in Fig. 4, to bring the lower cam surfaces 52 ofopposite heads into alignment with oscillatory arm 6l. In fact, it isimportant to note in connection particularly Figs. 3 to 6, inclusive,that downward shift g movements of the shifter arms [i9 and heads silfrom the neutral position of Fig. 3 to the forward drive position ofFig. 5 produce a similar upward shifting movement of shaft 2l andoscillatory arm 6'? imparted by the short rock arm 58, and that upwardshifting movements of the shifter arms 49 and heads 5B from the neutralposition of Fig. 3 to the reverse drive position of Fig. fl produce asimilar downward shifting movement of shaft 2| and oscillatory arm 5l,also imparted rock arm 68; the alignment of oscillatory arm 61 with camsurfaces 5f and ft2 being the result of compound movements in oppositedirections of heads 59 and oscillatory arm El and the shaft 2l.

Operation, Figs. 1 to 9, inclusive Assuming now that the engine 25 hasbeen started to produce continuous opposite direction rotation ofrollers 29 and 30 of both transmission mechanisms 28, operation of themachine will be as follows: So long as the shifting lever 53 is in itsintermediate neutral position of Fig. 1, the rollers 29 and 30 of bothfriction drive transmission mechanisms 28 will be spaced from theirrespective cooperating drums 3l and will idle freely withouttransmitting any power whatsoever to the drums. To shift thetransmission mechanisms 28 both into forward drive, the shifting lever53 is moved forwardly to bring the drums 3| of both transmissionmechanisms into frictional driving engagement with their respectivecooperating forward drive rollers 29. In overcoming the inertia of themachine at the start, the friction drive transmission mechanisms 28 willfunction as slippage clutches permitting the load to be picked upgradually or rapidly as desired, and, at all times, transmissionmechanisms 28 may be used as variable speed devices by controlling ofthe infinitely variable slippage factor thereof; the latter being undercomplete control of the operator. In

most instances, however, relatively positive or non-slippagetransmission of power will be desired from the rollers to the drum, andthis is accomplished by shifting the lever 53 to a position wherein thecompression springs 51 exert a considerable yielding pressure betweenthe drums and engaged rollers 29. Under these conditions, the vehiclewill travel in a forward direction with substantially no slippagebetween the engine-driven rollers and roller-driven drums Kso long asthe vehicle is steered or guided in a relatively straight line. However,when, under these same conditions, the direction of the vehicle issubject to change as a result of steering movements of the steering gearand steerable wheel 3, the outside drive wheel 2 will tend to run fasterthan the inside drive wheel, and this action will be automaticallypermitted by slippage, which will take place between the drum drivingthe outside wheel and the engaged roller, due to the fact that whendriving energy is transmitted from the drum to the cooperating roller,the drum and roller will tend to separate and permit relatively freeslippage. The automatic differential action thus achieved between thedrive wheels 2 is sufficient to permit relatively free directionalguidance of the machine throughout at least the intermediate steeringrange of the steering gear, and without producing any skidding of theground wheels 2, and without producing undue wear of the frictionalsurfaces of the drum and rollers.

From the foregoing, it will be understood that the machine will bedriven through both transmission mechanisms 28 and drive wheels 2 whenguided in a relatively straight line, but will be driven only by itsinside drive wheel 2 and cooperating transmission mechanism 28 whilebeing subject to direction changes responsive to movements of thesteering gear and steerable wheel 3 within the intermediate steeringrange thereof. However, when a relatively sharp turn in either directionis to be made, maneuverability of the machine is greatly facilitated bythe otherwise inoperative or ineffective steering gear-operatedtransmission mechanism, which will then come into play and function asfollows:

Assuming now that the vehicle is being driven forwardly and is subjectto a sharp turn to the right or left, the steering gear-operated arm B1,which is now in alignment with the upper end portions of cam surfaces 5Iof heads 5B, as shown in Fig. 5, will be brought into engagement withthe said upper end portion of the cam surface 5l of head 50 of theshifter arm 4S of the transmission mechanism 28 for the drive wheel 2 atthe inside of the right or left-hand turn being negotiated. Afterinitial engagement of the arm el with an engaged cam surface 5l, furtherturning movements of said arm 6'! responsive to further turningmovements of the steering gear and steerable wheel :i in the samedirection will cause an upward shifting of the engaged head E@ togetherwith its shifter arm 49 and power transmission drum 3l, first to theneutral drive position of Fig. 3 and then to the reverse drive positionof Fig. 4, against the action of cooperating compression spring 51. Whenthe transmission mechanism 28 `for the inside drive wheel is thusshifted into neutral, the drive from the engine will be immediatelytransferred from the inside drive wheel 2 to the outside drive wheel 2,and when the transmission mechanism 23 driving the inside drive wheel isfinally thrown into reverse drive, the opposite drive wheels E'.

flo

will be driven in opposite directions. It will be obvious that with thisarrangement, overall maneuverability of the machine is greatlyincreased, and exceedingly sharp turns may be negotiated with thegreatest of ease. In fact, the machine may he made to turn pivotallyabout a stationary vertical axis laterally intermediate the drive wheels2.

Now if we assume that the vehicle is being driven rearwardly, with bothtransmission mechanisms 28 positioned as in Fig. Ll, and is subject to asharp turn to the right or left, the steering gear-operated arm 5l,which will now be in alignment with the lower portions of cam surfacesli of heads 5t of both transmission mechanisms d, as shown best in Fig.4, will be brought into engagement with the said lower end portion ofcam surface 52 of the head 5B for the shifter arm de of the transmissionmechanism 28 for the drive wheel 2 at the inside cf the right orleft-hand turn being negotiated. After initial engagement of arm G1 withan engaged cam surface 52, further turning movements of the arm elresponsive to further turning movements of the steering gear andsteerable Wheel in the same direction will cause a downward shifting ofengaged head 5t, together with its shifter arm fig and powertransmission drum 3l, first into neutral drive position of Fig. 3, andthen to the forward drive position of Fig. 5 against the action ofcooperating compression spring 58, thereby accomplishing relativelyopposite drives exactly in the manner described above in connection withforward drive.

Description, Figs. 10 cmd 11 In these figures, parts corresponding toparts described in connection with Figs. l to 9, inclusive, will beindicated by like characters. The vehicle of these figures, althoughonly shown in fragmentary form, may be assumed to be like that shown anddescribed in connection with previously-described Figures l to 9,inclusive, with the single exception of the steering gear-operatedtransmission control mechanism. Hence, with the exception of thesteering gear-controlled transmission shifting mechanism, the machine ofthese Figs. 10 and ll will operate exactly as does the machine of Figs.l to 9, inclusive. In fact, the only function provided for in the deviceor apparatus of Figs. l to 9, inclusive, not provided for in themodified form of Figs. l0 and 11 is the automatic singular reversing ofthe transmissions 2s by the steering gearoperated transmission shiftingmechanism, as a result of extreme right cr left-hand turning movementsof the latter; the steering gear-operated shifting mechanism of Figs.l() and 1l functioning only to shift the transmission mechanism 23driving the inside drive wheel i into neutral drive, responsive toextreme right or left-hand turning movements of the steering gear.

in Figs. l0 and ll, the steering gear-operated sprocket 22 and segment2d are mounted fast on a frame-journalled shaft l5, which carries anoscillatory arm or head 'lil at its upper end. This oscillatory head orarm "iii is mounted fast on shaft i5 and is formed adjacent its outerend to provide a tongue il and laterally-spaced outwardly openingpin-receiving notches iS. The tongue 'il and notches "is cooperate withshifter pins 'le carried cy and upstanding from a laterally-spaced ofslide bars BQ that are provided at their front end portions with headsel for engagement with the cam surfaces iii and k1l 52 of shifter heads50 of oppositetransmission mechanisms 28. lByreference to Fig. 1l, itYwill be seen that the slide bars Si) extend longitudinally of themachine, are mounted for forward and rearward sliding movements in:hearing brackets E22 in transverse frame cross members 83, and are eachlaterally aligned with an opposite shifter head 59. By referenceparticularly to Fig. l0, it will he noted that the slide hars 8B andtheir heads 8i are vvertically aligned withr the vertical centers of theheads EE when'the latter are in their neutral-drive positions, shown inFig. 10. In Figs. l .and-ll, the bars 86 are both shown as retracted totheir normal inoperative positions, wherein they, in no way, influenceor obstruct shifting of the transmission mechanisms responsive to themanual control lever 53, rock shaft 54, rock arm 55, rigid link or rod56, and compression springs .'"l and In fact, throughout the entireintermediate s ing range of the steering gear, on either sic a straightline position thereof and the steerable wheel 3, the oscillatory arm orhead i6 will operate free and independent of the pins 19 of slide barsSil and produce no movement whatsoever of the latter. Howevenupon eX-treme right or. left-hand turning movements of the steering gear and itssteering post iii, the tongue 'il of oscillatory arm 'l5 will heTorought into engagement with the pin 'is at the inside of the turnbeing negotiated, wherehyfurther turning movements of the steering gearin the same direction will cause a forward shifting. of the engaged pin'i9 and its slide .har fit. If,

under such forward shifting movements of the.

slide har 8G, the transmission mechanisms 28 are in forward driveposition, the head Si of the forwardly shifted slide bar Si? will engagethe upper cam surface I of one of the shifter arms 49 and cause anupward shifting movement thereof back to neutral position of Fig. 10,whereas if the transmission mechanisms 28 are in reverse drive, theforwardly shifted head Si of the affected slide bar 8U will engage thelower cam surface 52 of engaged head 5c and shift the same downwardly toneutral position of Fig. 10.

While I have herein described several embodiments which my invention mayassume in practice, it will, of course, be understood that the same iscapable of further modification without departing from thc spirit andscope of the invention as expressed in the following claims.

What I claim is:

1. In a vehicle having laterally spaced drive wheels and a steerableground-engaging wheel spaced from the drive wheels, steering gear forthe steerable wheel, a driving engine, two power transmission mechanismseach. interposed between the engine and a laterally opposite drive wheeland each providing neutral and forward drive for its respective wheel,each such transmission mechanism comprising a different andindependently shiftahle control element having neutral and forward drivepositions, common primary control mechanism for the two transmissionmechanisms; said common primary transmission control mechanismcomprising a primary manually shiftable control element having forwarddrive and neutral positions, and branch operating connections extendingfrom said common primary control element each to a different one of saidindependently shiftahle transmission elements and each comprising aresilient link; and steering gear voperated control mechanism for saidtransmission mechanisms; said steering gear. operated. control mechanismcomprising a common actuating element loperativelyconnected to anddriven from the steering gear, branch operatingfconnections eachoperatively associated withV the common actuating element, said branchoperating-connections each being operatively connected tothe shiftablecontrol element of a different one of said transmission mechanismsindependently of the associated resilient linltof`V the primary controlmechanism; saidresilient linksibeingin an unloaded co tion whenv thecommon primary control me nism is in itsneutral position and being loeed when the common primary control mechan' is in drive positionV andwhen in such loaded cc dition being-further .yieldahlein the direction`causing such .loading-to allow over-riding con.-

trol by thesteeringgear operated control meehanism.

2..In a vehicle havinglaterally-spaced drive wheels and .a steerableground-engaging wheel spaced fromthe drive wheels, steering gear for thesteerable wheel, a ldrivingy engine, two rpower transmissionmechanismseach interposed hetween the engine-and a laterally opposite drivewheelandreach providing neutral and for` ard driveforitsrespectivewheel, each such ti .smission mechanism comprising adiierent and independently shiftableelement having neutral and forwarddrive positions, common primary control `mechanism for `the twotransmission mechanisms; said common primary transmission ,controlmechanism. comprisingv a primary inanually shiftable controlelementhaving forward. and neutral drivepositicns and branch operatingconnections vextending from said common primarycontrol element each toa` different one of saidr independently shiftable transmission elementsand each comprising a resilient link; and steering gear operatedtransmission control meehanism for shifting one of the transmissionmechanisms from, forward drive to neutral responsive to steeringmovements ofthe steering gear in one ,direction andforshifting the otherof the transmission mechanisms from forward drive to neutral responsiveto steering movements of the steering gearin the other direction; saidsteering gear operated transmission control mechanismcomprising two camfollowers each operatively associated with the shiftableelement of adifferent one of said transmission mechanisms and connectedtheretoindependently of said resilient links of the common primary controlmechanism, and cam means operatively connected to the steering gearforoperation therefrom and being operatively associated with said two camfollowers, said resilient 4links being in an unloaded condition vwhenthe common primary control mechanism is in neutral position being loadedwhen the common primary control mechanism is in drive Aposition and whenin such loaded condition being further yieldaole in the directioncausing such loading to allow over-riding ccntrol'by the steering gearvoperated control mechanism.

3. In a vehicle having laterally spaced drive wheelsand Vasteerableground engaging wheel spaced from the drive wheel, .steeringgear for the steerahlewheel, a driving engine, two power transmissionmechanisms each interposed hetween the engine and a laterally oppositedrive wheel and eachproviding neutral and Vforward and reverse drive forits respective wheel, each such transmission mechanism comprising adifferent ,and independently shiftable element having neutral andforward and reverse drive positions, common primary control mechanismfor the two transmission mechanisms; said common primary transmissioncontrol mechanism cornprising a primary manually shiftable controlelement having forward and neutral and reverse drive positions, andbranch operating connections extending from said common primary controlelement each to a different one of said independently shiftabletransmission elements and each comprising a resilient link; and steeringgear operated transmission control mechanism; said steering gearoperated transmission control mechanism comprising two pairs ofrelatively oblique carn followers of which each pair is operativelyassociated with the shiftable element of a different one of saidtransmission mechanisms and is operatively connected theretoindependently of said resilient links of the primary control mechanism,steering gear operated cam means, and operative connections between thesteering gear and said cam means, said cam means defining two pairs ofcam surfaces, each cam surface being operatively associated with arespective follower, the cam followers having neutral and forward and.reverse drive positions, means mounting and guiding the cam means formovements of its cam surfaces in predetermined paths of travelresponsive to steering action of the steering gear, one cam follower ofeach pair thereof being disposed in and obliduely of the path of travelof its associated cam surface when said cam followers are in theirreverse drive positions, said resilient linlzs being in an unloadedcondition when the common primary control mechanism is in its neutralposition and bemg loaded when the common primary control mechanism is indrive position and when in such loaded condition being further yieldablein the direction causing such loading to allow overriding control by thesteering gear operated control mechanism.

4. ln a vehicle having laterally spaced drive wheels and a steerableground engaging wheel.

spaced from the drive wheel, steering gear for the steerable wheel, adriving engine, two power transmission mechanisms each interposedbetween the engine and a laterally opposite drive wheel. and eachproviding neutral and forward and reverse drive for its respectivewheel, each such transmission mechanism comprising a different andindependently shiftable element having neutral and forward and reversedrive posicommon primary control mechanism for the two transmissionmechanisms; said common primary transmission control mechanismcomprising a primary manually shiftable control element having forwardand neutral and reverse drive positions, and branch operatingconnections extending from said common primary control element each to adiiferent one of said independently shiftable transmission elements andeach comprising a resilient link; and steering gear operatedtransmission control mechanism; said steering gear operated controlmechanism comn prising two pairs of relatively diverging cam followersof which each pair is operatively associated with the shiftable controlelement or a different one of the transmission mechanisms and isoperatively connected thereto independently of said resilient links ofthe primary control mechanism for shifting movements with saidassociated shiftahie control element between neutral and forward andreverse drive positions, and cam means operatively connected to thesteering gear for movements generally toward and from the cam followers,means mounting and guiding the cam means for such movements, thesteering gear moving the cam means in the direction of one pair of camfollowers and away from the other pair of cam followers responsive tosteering gear movements in one direction and toward the said other pairof cani followers and away from the first said pair of cam followersresponsive to movements in the other direction, when in their neutralpositions the relatively diverging cam followers of each pair thereofbeing disposed at opposite sides of the field of movement of the cammeans, when the cam followers are in their forward drive positions onecam follower of each pair thereof being disposed in the field ofmovement of the cam means, and when the cam followers are in theirreverse drive positions the other cam follower of each pair thereofbeing disposed in the field of movement of the cam means, said resilientlinks being in an unloaded condition when the common primary control.mechanism is in its neutral position and being loaded when the commonprimary control mechanism is in drive position and when in such loadedcondition being further yieldable in the direction causing such loadingto allow overriding control by the steering gear operated controlmechanism.

5. rThe structure donned in claim fl in which the means for mounting andguiding the cam also mounts and guides the cam means for movements in aplane that is angular to a direction of steering gear imparted movementthereof, the cam means having neutral and forward drive and reversedrive positions in said plane of movement and the latter two of whichpositions spaced at opposite sides of neutral position thereof, andoperating connections between the primary manually shiftable controlelement oi' the common primary control mechanism and said cam means forshifting the cam means in said plane of movement from neutral positionto forward drive position responsive to forward shifting movements ofthe primary manually shiftable control element and shifting the cammeans in said plane from neutral position to reverse drive position insaid plane responsive to reverse shifting movements of the primarymanual control element of the primary control mechanism.

G. In a vehicle having laterally spaced drive wheels and a steerableground engaging wheel spaced from the drive wheel, steering gear for thesteerable wheel, a driving engine, two power transmission mechanismseach interposed between the engine and a laterally opposite drive wheeland each providing neutral and forward and reverse drive for itsrespective wheel, each such transmission mechanism comprising adifferent and independently shiftable element having neutral and forwardand reverse drive posi-- tions, common primary control mechanism for thetwo transmission mechanisms; said common primary transmission controlmechanism coinprising a primary manually shiftable control elementhaving forward and neutral and reverse drive positions, and branchoperating connections extending from said common primary con-- trolelement each to a different one of said independently shiftabletransmission elements and each comprising a resilient link; and steeringgear operated transmission control mechanism; said steering gearoperated control. mechanism comprising two pairs of relatively divergingcam followers of which each pair is operatively associated with theshiftable control element of a different one of the transmissionmechaniev ns and is operatively connected thereto index endently of saidresilient links of the primary control mechanism for shifting movementswith said associated shiftable control element between neutral andforward and reverse drive positions, and single cam means selectivelyengageable with the two pairs of cam followers, means mountingr andguiding the cani means for generally horizontal movements tov-Jard andfrom the cam follower and for generally vertical moveu ments betweenneutral and forward and reverse positions, operating connections fromthe steering gear to the cam means for imparting the cto said horizontalmovements generally toward and. from the cam followers, and operatingconnections between the primary manually shiitabie control element ofthe primary control mechanism and the cam means for imparting said vertical movements to the cam means between neutral and forward and reversepositions in correspondence with the movement of the primary manualcontrol element to such positions, said resilient links being in anunloaded condition when the common primary control mecha). in itsneutral position and being loaded when the common primary controlmechanism in drive position and when in such loaded connition beingfurther yieldable in the direction ing such loading to allow overridingcontrol by the steering gear operated control mechant '7. In a vehiclehaving the manually controlled power steering mechanism as set forth inclaim l, in which said friction drive transmission meen` anism comprisesan engine driven roller element and roller-driven drum element, meansmounting and guiding one of said elements for relative shiftingmovements toward and from other thereof, and means for relativelyshifting the cooperating roller and drum elements or said t nsmissionmechanisms into and at ci 'notional driving engagement to provideneutral ad variable speed friction drive to the cooper `tive drivewheels, the angle and direction of of the cooperating drain and rollerelem nts being such that resistance to forward driving energytransmitted by t'ne roller elements to the drinn elements will increasethe pressure between the cooperating roller and drum elements an warddriving energy transmitted by the L' elements to the roller elementswill reduce the pressure between the cooperating roller elements,whereby the ele relatively free to run ahead of their coop rollerelements to allow directional, sie; the vehicle responsive to steeringnts ci the steeraole wheel without skidding the ground whee ReferencesCited in the le of this patent UNITED STATES PATENTS Number Name Date281,813 Willson July 2e, 1883 503,047 Pickering Apr. 1898 1,302,769Crellin May 6, 1919 1,686,553 Krotz Aug. le, 1928 FOREIGN PATENTS NumberCountry Date 20,319 Switzerland Aug. 3l, 1899 22,439 Great Britain 139'!26,415 Great Britain 13.96

